Nitrogen Cycle: N₂ gas is unusable. Bacteria fix N₂ into ammonia (NH₃) and nitrates (NO₃⁻) for plants to absorb.
Phosphorus Cycle: SLOW process. No atmospheric gas phase. Relies on rock weathering to release phosphates into soil.
Macromolecules: Nitrogen is used in Amino Acids and DNA/RNA. Phosphorus is used in DNA, RNA, ATP, and Phospholipids.
Tags
EcologyNitrogen FixationMacromoleculesBacteria
Select Biogeochemical Cycle
The Nitrogen Cycle: The atmosphere is 78% Nitrogen Gas (N₂), but strong triple bonds make it useless to plants. Soil and root-nodule Rhizobium Bacteria "fix" N₂ into Ammonia/Nitrates. Plants absorb this to build Proteins and Nucleic Acids. Denitrifying bacteria complete the cycle by returning N₂ to the air.
AP Exam Connection
You MUST know which cycle builds which macromolecules. • Nitrogen -> Proteins, Nucleic Acids (DNA/RNA). • Phosphorus -> Nucleic Acids, ATP, Phospholipids.